The mid-twentieth century avant-garde activity known as “psychogeography” experienced a significant, if largely unexamined revival during the 1990s. This thesis investigates the instances of extra-institutional cultural practice that drove this revival, primarily in a UK context. The exploration of psychogeography thus becomes a kind of Archimedean point: developing new angles on both the avant-garde practices of Surrealism and the Situationist International, but also a detailed initial exploration of these 1990s activities. Psychogeography is used to discern congruencies and shifts between the two moments, ultimately seeking to resituate them in relation to the present, opening new perspectives on continuing practices. Conventional narratives concerning psychogeography’s development present the purported political radicality of its Situationist form being displaced and “recuperated” by later aestheticised iterations. I contest this on three levels. Firstly, I suggest psychogeography can lay no such claim to a founding radicality. Destabilising its origins, I offer an expanded understanding of the practice, uncovering roots and routes in overlooked locales. Secondly, developing Asger Jorn’s under-examined method of “triolectics”, emergent, in my reading, in complementary relation to the Surrealist concept of “objective chance”, I use this to map psychogeography’s post-Situationist iterations, examining flourishing and in many ways more radical instances of material visual culture, in relation to which, accusations of “recuperation” appear misplaced. Thirdly, Jorn’s “triolectical” approach informs a complementary historiography: rather than define psychogeography as either some fixed essence, or series of equivalent variations, I present a development more in keeping with what Jorn called a “transformative morphology of the unique”. Psychogeography, I argue, has no fixed ontology, radical, recuperated or otherwise. Rather it functions as a constellation of social relations, itself a “situation”, variously connecting continually emergent fields of both resistant but also more overtly valorising material cultural practices.